Classical tools for measuring material properties of a material comprising mineral binders and polymers are for example the Vicat test, penetrometer, rheometer, needle penetration, or compression testing equipment like e.g. from Instron®. These tools, however, cannot be used for monitoring the complete time evolution of the chosen material properties.
Ultrasonic analysis methods for measuring material properties of mineral binders are known. U.S. Pat. No. 5,412,990 discloses a method and apparatus for determining the setting time of a cement slurry using acoustic shear wave signals. U.S. Pat. No. 6,655,213 discloses a method for examining a solidifying and/or hardening material using ultrasound waves.
Existing ultrasound devices used for the characterization of Theological and mechanical properties of a material operate over a narrow range of high frequencies. This approach is satisfactory for homogeneous elastic materials only. In materials with air bubbles, porosity, cracks and/or inclusions that have a different ultrasonic response than the matrix, the material response can be more complex. In particular, it is often not possible to obtain true fundamental material properties without specific calibration.
The main disadvantage of the known devices is that they can only be used over a narrow range of frequencies, whereas dynamic elastic properties of a material can strongly depend on the excitative frequency. In addition, the devices known in the art are heavy and cumbersome, have high energy consumption and are therefore not suitable for easy on site measurement. Furthermore, existing devices do not offer direct display of material properties and rely on data processing subsequently to the measurement which is time consuming. Furthermore, existing devices have a high signal to noise ratio. Thus, there is a growing need for a non-destructive technique that can follow the direct time evolution of the dynamic elastic modulus of a material and for an apparatus that offers a high degree of portability and user friendliness.